Bottle can member, bottle, and thread forming device

ABSTRACT

An effective thread number in the thread section which is disposed on the mouth section of the bottle is formed to be 2.2. That is, the thread section is formed such that the thread section  13  should serve effectively in the mouth section such that an interval between a start position and an end position should be 2.0 to 2.5. In the bottle can member  11  which has such a thread section, an outer diameter of the thread section which is formed on the mouth section is 28 to 38 mm. Also, the thickness of the mouth section is 0.25 to 0.4 mm. The thread section which has the effective thread number 2.0 to 2.5 is formed by eight-thread per inch pitch. By doing this, it is possible to put the cap desirably.

CROSS-REFERENCE TO PRIOR APPLICATION

This is a U.S. national phase application under 35 U.S.C. §371 ofInternational Patent Application No. PCT/JP02/13840 filed Dec. 27, 2002,and claims the benefit of Japanese Patent Application Nos. 2001-401686filed Dec. 28, 2001; 2002-193465 filed Jul. 2, 2002; 2002-197799 filedJul. 5, 2002 and 2002-233917 filed Aug. 9, 2002 which are incorporatedby reference herein. The International Application was published inJapanese on Jul. 17, 2003 as WO 03/057572 A1 under PCT Article 21(2).

TECHNICAL FIELD

The present invention relates to a metal bottle can, a thread formingdevice in which a thread section is formed on a mouth section.Furthermore, the present invention relates to a method for forming amouth section.

BACKGROUND ART

A so-called bottle can member 1 which is formed by a drawing operationfor a metal bottle member has a thread section 3 on a mouth section 2and an outer periphery on an aperture section of the bottle can member 1which is formed in a cylindrical shape which has a bottom section asshown in FIG. 6A. A product such as a drink water are filled in thebottle can member from the thread section 3. After that, an outerperiphery of a cap 5 is compressed in accordance with the thread section3. By doing this, the cap 5 is put thereon as shown in FIG. 6B. The cap5 comprises a cap main upper section 6 to which a cap thread section 7is formed in accordance with the thread section 3 of the bottle canmember 1 and a cap main bottom section 9 which is formed on a bottom endof the cap main upper section 6 so as to expand over the bottom sectionof an expanding section 4.

Also, before the cap 5 is put has a shape like a cap member 5′ as shownin FIG. 6C such that an upper section is ceiled by a ceiling plate andits bottom section has an aperture section orthogonally in a downwarddirection so as to be a cylindrical shape. A score 8 a which is formedin a plurality of cutting sections which are formed in a circumferentialdirection and a bridge 8 b are disposed alternatively in a bridgesection 8 such that the cap main body bottom section 9 is connected viathe bridge section 8.

In order to remove the cap 5 from the bottle can member 1, a relativerotative force is applied to the cap 5 and the bottle can member 1. Sucha rotative force serves such that the cap 5 should be moved upwardly bythe thread section 3. However, the cap main body bottoms section 9 isengaged to an expanding section 4 of the bottle can member 1; therefore,the bridge 8 b is broken; thus, the cap main body upper section 6 andthe cap main body bottom section 9 are separated. Consequently, the capmain body bottom section 9 remains in the mouth section 2; thus, the capmain body upper section 6 is removed from the bottle can member 1. Thatis, the cap is opened on the bottle can member 1 by rotating the cap 5by a user such that the bridge section 8 should be broken.

Conventionally, in the bottle can member 1 which has such a threadsection 3, a diameter of an aperture section of a bottomed cylindricalbottle can member 1 as shown in FIG. 7A is reduced temporarily as shownin FIG. 7B. After that, as shown in FIG. 7C, a predetermined distancefrom the aperture end of the mouth section 2 is enlarged so as to forman enlarged diameter section 2′. Furthermore, as shown in FIG. 7D, athread section 3 is formed in a constant distance from the aperture endsuch that an enlarged diameter section in which the thread section 3 isnot formed remains for an expanding section 4; thus, the expandingsection 4 is formed.

For an outer diameter A of the cap 5 which is put on the bottle canmember 1 as shown in FIGS. 6A to 6C, there are three standards such as28 mm, 33 mm, and 38 mm. An outer diameter B of the mouth section 1 ofthe bottle can member 1 is formed so as to be smaller than the outerdiameter A of the cap 5. If the cap 5 which has 38 mm outer diameter isput to the thread section 3, the thread section 3 is formed so as tohave an effective thread number approximately 1.5 to 1.7 which serve asa thread effectively.

Here, the effective thread number indicates a thread number for aneffective thread section which is shown in FIG. 8. FIG. 8 is a view forexplaining an over view for the thread section 3 in which Y and Z areincomplete thread sections. W indicates a perfect thread section. Cindicates a center point. The thread section 3 is formed by a mountainsection 3 a and a valley section 3 b. The incomplete thread section Y isformed in a starting side of an upper end of the mouth section 2. Theincomplete thread section Z is formed an ending side of a base end sideof the mouth section 2. Outer diameters for the mountain section 3 a andthe valley section 3 b for a perfect thread section W between theincomplete thread section Y and the incomplete thread section Z areformed in predetermined diameters respectively. The diameter of the peakof the thread of the incomplete thread section Y increases graduallyfrom an end point Y1 toward a starting point W1 of the perfect threadsection W. The diameter of the valley of the thread of the incompletethread section Z increases gradually from an end point W2 of the perfectthread section W toward the end point Z2.

The effective thread section X includes entire perfect thread section Wwhich covers an effective thread starting point X1 which is in a middleof the incomplete thread section Y. The effective thread section X is athread section which covers an effective thread end section X2 which isin a middle of the incomplete thread section Z. The effective threadstarting point X1 is a cross point which is made by a bisector L1 whichdivides an acute angle ∠α for an incomplete thread section Y which isformed by an end point Y1, a center point C, and a starting point W1 andan incomplete thread section Y. An effective thread end point X2 is across point which is formed by a bisector L2 for an acute angle ∠β forthe incomplete thread section Z which is formed by an end point W2, acenter point C, and an end point Z2.

However, in a conventional bottle can member 1, if the effective threadnumber n the thread section 3 which is disposed in the mouth section 2of the bottle can member 1 is approximately 1.5 to 1.7, a section inwhich there are two threads which are disposed toward a tip section froma base end section of the mouth section 2 and a section in which thereis only one thread occur; thus, such a difference of the threads causesa problem. That is, if the thread number is formed as explained above,if a cap 5 is put on the bottle can member 1 such that a pressure in thebottle should be positive, a force is applied which pushes up the cap 5.A force for engaging the cap 5 is weak in a section in which there isonly a thread; therefore, the cap 5 is disposed undesirably upwardly.That is, the cap 5 is disposed partially to the bottle can member 1;thus, a bridge 8 b is strained in a section in which there is only athread; thus, the thread is broken. That is, there has been a problem inthat a bridge is broken. Also, the thread section 3 is compressed whenthe cap is put thereon more greatly than in a case in which there aremore threads. Therefore, unequal sealing capability occurs in acircumferential direction; thus, there is a concern that there is areduced airtight condition.

For resolving such a problem, there is a proposal for increasing theeffective thread number. However, in a step for putting a cap 5 on thebottle can member 1, if a diameter of the cap is approximately 28 mm,the cap is pressed on the bottle by approximately 900 N force so as towind up the cap therearound. However, if the diameter of the cap is 33mm or greater, the force in the bottle for pushing up the cap is sogreat that a greater area for operating a molding operation isnecessary. Therefore, the cap is compressed toward a ceiling surface ofthe bottle can at 1050 to 1200 N force by using a pressure block so asto wind up the cap therearound.

For example, if the effective thread number is 2.5 to 3, there are asection in which there are two threads and a section in which there arethree threads. Therefore, in a step for molding a cap thread section 7which is explained above, the section in which there are three threadsmay be deformed more easily than the section in which there are twothreads. In such a case, a relative position between the position forcompressing the cap by a thread forming roller and a position of astarting point W1 in a complete thread section W is shifted in an axialdirection undesirably; thus, there is a section in which a thread isformed insufficiently. Also, a force is generated for raising a bottomsection near a side section of the cap 5 in a axial line directionupwardly; thus, a bridge may be broken more easily if there are morethreads. Therefore, if there is a section in which there are threethreads, a bridge is broken more easily. In addition, after completingthe winding operation for the cap, a pressure block is released. Asection in which there are three threads serves as a spring so as topush up the cap. Therefore, a bridge near a section in which there arethree threads may be broken more easily than a section in which thereare two threads. Also, if the thread number is 3 or greater, a torquefor opening a cap increases and a number for winding the cap alsoincreases. Therefore, a user have to take more time and efforts foropening a cap accordingly; thus, such a case is not preferable.

If there is not a case in which a bridge is broken in a cap 5 due to aninner pressure of the bottle, an interval therebetween extends if theinterval between the cap thread section 7 of the cap 5 and a ceilingsurface is long; thus, there is a problem that a contact of the capdecreases. Also, if an interval between the cap thread section 7 of thecap 5 and the ceiling surface is narrow, the mouth section 2 cannotendure a force in a step for compressing the cap 5 thereon; thus, themouth section 2 may be deformed undesirably.

Also, in a conventional technique, a bottle can which is commonly usedfor a can for a beverage is produced by a drawing operation by drawing ametal plate which is made of an aluminum and an aluminum alloy and anironing operation which is supposed to be performed consequently. Such acan is called a DI can commonly. A mouth section is formed on an uppersection of the DI can. After filling a content in such a bottle can, acap is put on the mouth section of the bottle can; thus, a capped bottlecan is produced.

Conventionally, a capped bottle can 101 which is shown in FIG. 11 isclosed in an airtight manner by putting the cap 103 on the bottle can102. A male thread section 105, an expanding section 106, and a curlsection 107 are formed on the mouth section 104 which is disposed in thebottle can 102. The ceiling surface section 108, a female thread section109, a pilfer proof section 110, and a bridge section 111 are formed inthe cap 103 such that a liner 112 which is a sealing member is appliedon an inner surface of the ceiling surface section 108. The cap 103 isattached to the bottle can 102 such that the male thread section 105 ofthe bottle can 102 and the female thread section 109 fit together andthe bottom end section of the pilfer proof section 110 expands over theexpanding section 106; thus, the cap 103 is sealed while the curlsection 107 and the liner 112 contacts tightly. Also, the capped bottlecan 101 has a structure so as to endure a predetermined inner pressurein case that the content thereinside is a carbonated beverage.

In order to open the capped bottle can 101, when the cap 103 is rotatedwith reference to the bottle can 102, the female thread section 109 isguided by the male thread section 105 so as to be moved upwardly. Abridge section 111 is cut by engaging the expanding section 106 and thepilfer proof section 110; thus, the curl section 107 and the liner 112are separated. Furthermore, the cap 103 is removed from the bottle can102 by rotating the cap 103. In such a case, when the cap 103 is rotatedfor opening the cap 103, a knurl section 113 is formed on the cap 103.The knurl section 113 is formed in an upper section of the female threadsection 109 such that concave sections are formed periodically onprotruding sections which have arc cross section which are disposed in acircumferential direction.

Also, in a step for winding the cap 103 on the bottle can 102, a capmember on which the female thread section 109 and the pilfer proofsection 110 are not formed is applied on the bottle can 102. While aforce is applied in a direction in which the cap member is compressed tothe bottle can 102, the female thread section 109 and the pilfer proofsection 110 are formed along the shape of the male thread section of thebottle can 102 and the shape of the expanding section 106. The curlsection 7 and the liner 112 contacts more desirably by winding up thecap 3 while applying a force; thus, a more desirable sealing conditioncan be realized. In such a case, the effective thread number for malethread section and the female thread section 109 is formed to beapproximately 1.5 to 1.7.

By the way, in the bottle can 102 to which the above cap 103 is put, ifa pressure which is lower than a predetermined inner pressure is appliedto the ceiling surface section 108 on the cap 103 and an intervalbetween the female thread section 109 on the cap 103 and the ceilingsurface section 108 is long, the interval extends: thus, there is aproblem in that a contact between the curl section 107 and the liner 112may be reduced. Also, a knurl section 113 is formed between the femalethread section 109 on the cap 103 and the ceiling surface section 108;thus, there is a problem that the interval extends further.

Also, in order to solve such problems, it is possible to propose an ideain which an interval between the female thread section 109 on the cap103 and the ceiling surface section 108 should be narrowed; that is, aninterval from the male thread section 105 on the bottle can 102 to theupper end surface of the curl section 107 should be maintained in a lowposition. In such a case, there is a problem in that it bendsundesirably because of insufficient rigidity against the pressing forceto the cap 103 in a step for putting the cap 103.

Also, the effective thread number of the male thread section 105 isapproximately to be 1.5 to 1.7; thus, there is a section in which thereis a thread and there is a section in which there are two threads fromthe base end section of the mouth section 104 toward the tip section.Thus, there is a problem in that an engaging force in the male threadsection 105 and an engaging force in the female thread section 109 arenot constant over a circumferential direction of the mouth section 104.Because of this, even if the inner pressure in the bottle can 102 towhich the cap 103 is put is at a predetermined inner pressure or lower,the cap 103 is shifted upwardly undesirably in a section in which thereis a thread of which engaging force is weak; thus, there is a problem inthat the contact between the curl section 107 and the liner 112 isreduced. Also, if the effective thread number is increased to be 2.5 ormore so as to enhance the engaging force, there is a problem in that atorque for opening the cap needs to be greater.

Furthermore, in a conventional technique, in a so called bottle canmember, a mouth section is formed in an aperture section of the bottlecan member which has a bottomed cylindrical shape and a thread sectionis formed such that the cap should be put around an outer periphery ofthe mouth section.

In order to produce a bottle can member which has such a thread section,a bottle can member which has a bottomed cylindrical shape is producedin advance. As shown in FIG. 19A, a diameter of the aperture section ofthe bottle can member is reduced once so as to form a mouth section 202.After that, the diameter is enlarged by a predetermined distance from anend of the aperture end of the mouth section 202 so as to form anenlarged diameter section 202 as shown in FIG. 19B. After that, a threadsection 203 is formed at a predetermined distance from the aperture endby a thread forming device as shown in FIG. 19C. In such a case, whenthe thread section 203 is formed in the mouth section 202, an expandingsection 204 is formed by maintaining a diameter enlarged section inwhich a thread section 203 is not formed.

In the conventional thread forming device, although it is not shown inthe drawings, an inner core which contacts an inner surface of the mouthsection 202 and an outer core which contacts an outer surface of themouth section 202 rotate around an axial center of the bottle can member201 while sandwiching the mouth section 2 with each other; thus, thethread section 203 is formed around an outer surface of the mouthsection 202. In such a case, the thread number of the thread section 203which is formed on the mouth section 202 is approximately 1.7 as shownin FIG. 19C.

Also, after that, in the bottle can member 201 on which the threadsection 203 is formed, a tip of the mouth section 202 is bent fromthereoutside to thereinside. After various steps for putting the cap forforming the curl section 208 as shown in FIG. 20, a content is filledthereinside; thus, the cap 205 is put shown in the drawing so as to sealthere.

As explained above, in the conventional thread forming device, an innercore which contacts an inner surface of the mouth section 202 of thebottle can member 201 and an outer core which contacts an outer surfaceof the mouth section 202 rotate around an axial center of the bottle canmember while sandwiching therebetween; thus the thread section 203 isformed which has a thread number 1.7 in the mouth section 202 of whichdiameter is enlarged.

However, if the thread number of the thread section is approximately1.7, as shown in FIG. 20, there is a problem in that there is a sectionin which there two tread sections 203 on an peripheral surface of themouth section 202 and there is a section in which there is only onethread section 203; thus, such a difference between the thread sectionscauses a problem. That is, if there is thread number which is explainedabove, if a pressure in the bottle can member 201 is positive when thecap 205 is put on the bottle can member 201, a pressure which pushes upthe cap 205 is applied there; thus, the cap 205 is shifted upwardlyundesirably. Therefore, the cap 205 is disposed partially with referenceto the bottle can member 201; thus, a bridge 207 which is disposedbetween scores 206, 206 near the aperture end of the cap 205 is strainedand broken. Thus, there is a problem in that there is a so-called abroken bridge.

In order to solve the above problems, it is tried to form a threadnumber 2.2 as shown in FIG. 21 by increasing the thread number of thethread section 203. When the thread section 203 which has 2.2 threadnumber on the mouth section 202 of the bottle can member 1 in this way,there is a thread section in which there are a first thread 203 a, asecond thread 203 b, and a third thread 203 c for the thread section 203between the starting section 203A of the thread section 203 and the endsection 203B.

By the way, when the thread section 203 which has 2.2 thread number isformed on the bottle can member 201 which has a thread area which hasthe above three threads, after that, a curl section 208 is formed forforming the curl section 208 on a tip of the mouth section 202 in a stepfor putting the cap while compressing the tip of the mouth section 202by a cap putting device in a direction which is disposed toward thebottom of the bottle can member.

However, in such a case, the thread section 203 which has three threadsections is disposed; thus, a distance from the first thread 203 a tothe curl section 208 is close. Therefore, in a step for putting the cap,the first thread 203 a of the thread section 203 is crushed because itis compressed downwardly by a compressing force by the cap puttingdevice. Therefore, as shown in FIG. 22, a diameter of the first thread203 a is enlarged in a radial direction such that the first thread 203 aprotrude by A from a height of the second thread 203 b and the thirdthread 203 c in a circumference direction undesirably.

If the first thread 203 a of the mouth section 202 is protruding in acircumferential direction ad the cap 20 is put on the bottle can member201 consequently, the cap 205 is put thereon according to a shape of themouth section 202; therefore, as shown in FIG. 22, a diameter of theaperture of the cap 205 is smaller than the outer diameter of a bottlethread 203 a. Here, the cap 5 is shown in FIG. 22 under condition that apart of the cap 5 is broken.

The cap 205 which is put thereon under the above explained condition isremoved from the bottle can member 201 such that the user can use it fordrinking a content therein. Also, the mouth section 202 can be screwedso as to seal the mouth section when the user stops drinking the contenttherein. However, if the diameter of the end of the aperture of the capis smaller than the diameter near the ceiling, a resistance between themouth section 202 and the cap 205 is so great that a larger torque forclosing the cap is necessary. Thus, there is a problem in that it issometimes hard for handling it.

DISCLOSURE OF THE INVENTION

The present invention was made in consideration of the above problems.An object of the present invention is to provide a bottle can member anda bottle to which a cap is put in which a bridge should not be broken onthe cap which is put on the mouth section of the bottle can member suchthat it is possible to put the cap desirably.

Also, other object of the present invention is to provide a metal bottlecan which has a folding rigidity in which the mouth section of the metalbottle can be sealed by the cap reliably.

Furthermore, other object of the present invention is to provide amethod for forming the mouth section of the bottle can member in whichit is possible to form all thread sections of the mouth sectionapproximately equally with regardless to the steps for putting the cap.Yet, other object of the present invention is to provide a method, abottle can member, and a bottle for forming the mouth section of thebottle can member in which it is possible to perform the above methodreliably.

In order to achieve the above objects, the present invention proposesdevices and methods below.

An invention according to a first aspect of the present invention ischaracterized to be a bottle can member in which a thread section isformed in a mouth section of a metal bottle can member which has abottomed cylindrical shape such that an outermost diameter of the threadsection which is formed on the mouth section is 28 to 38 mm, a thicknessthere is 0.25 to 0.4 mm, and an effective thread number of the threadsection is formed to be 2.0 to 2.5.

According to the bottle can member of the present invention, theeffective thread number of the thread section of the mouth section is2.0 to 2.5; therefore, if the cap is put on the bottle can member, thebridge is not broken, nor an insufficient thread section is not formed.In addition, the torque for opening the cap and the rotating number forthe cap do not increase unnecessarily; thus, the cap is put desirably.More preferably, if the thread section is formed such that the threadnumber is 2.0 to 2.3, the cap is put more preferably. It is becauseincomplete thread sections Y, A overlap in an axial direction if theeffective thread number is smaller than 2.0; thus, it is not possible toform the thread stably. Also, by forming the effective thread number by2.0 to 2.5, a compressing amount for the mouth section in an axialdirection when the cap is put is approximately equal over acircumferential direction; thus, it is possible to enhance a sealingcondition. Here, it is more preferable if an outermost diameter of thethread section is 31 to 38 mm.

The invention according to a second aspect of the present invention is abottle can ember of the first aspect in which the thread section whichis formed on the mouth section of the bottle can member is formed in apitch of eight-thread per inch.

According to the bottle can member according to the present invention,the thread section of the mouth section is formed by a pitch such as theeight-thread per inch; thus, it is possible to form a desirable threadsection for such type of the bottle can member.

The invention according to a third aspect of the present invention is abottle can member according to the first or the second aspect in which,under condition that an outer diameter of the thread which passesthrough a thread start point is indicated by D1, and an outer diameterof a curl section which passes through the outermost diameter section ofthe curl section is indicated by D2, a height h from the thread startpoint of the thread section to an upper end surface of the mouth sectionis in a range of 0.7≦(D1−D2)/h≦1.

According to the bottle can member of the present invention, undercondition that an outer diameter of an outer diameter of the threadwhich passes through the start point is indicated D1, and an outerdiameter of a curl section which passes through the outermost diametersection of the curl section is indicated D2, the mouth section is formedsuch that the height h from the thread start point of the thread sectionto an upper end surface of the mouth section should be in a range of0.7≦(D1−D2)/h≦1, a length of an interval between the female threadsection of the cap and the ceiling surface and an outer diameter of thecap are specified so as to correspond to the formed mouth section.Therefore, the interval between the female thread section of the cap andthe ceiling surface hardly extend due to an inner pressure of the bottlecan to which the cap is put. Furthermore, it is preferable that themouth section should be formed such that the height h should be in arange of 3.24 mm≦h≦5.6 mm so as to restrict such an extension. By doingthis, it is possible to maintain the contact between the bottle canmember and the cap desirably.

The invention according to a fourth aspect of the present invention ischaracterized to be a bottle can member of the first to the third aspectin which the slant angle θ in the slant section is set to be in a rangeof 33°≦θ≦55°.

According to the bottle can member according to the present invention,the mouth section is formed such that the slant angle θ of the slantsection which is disposed upwardly from the thread start point of thethread section to an upper section above the mouth section should be33°≦θ≦55°. Therefore, the mouth section is formed so as to endure thecompressing force by the cap in the step for putting the cap. By doingthis, it is possible to form a bottle can member which has a highfolding rigidity.

The invention according to a fifth aspect of the present invention ischaracterized in that the cap is put on the mouth section of the bottlecan member according to the first to the fourth aspect.

According to the bottle of the present invention, the effective threadnumber of the cap thread section is formed to be 2.0 to 2.5; thus, thebridge is not broken. Thus, the cap is put on the bottle can memberdesirably.

The invention according to a sixth aspect of the present invention ischaracterized in that, in a method for forming a mouth section of thebottle can member for forming a thread section which has a plurality ofstages of threads from a tip of the mouth section toward a direction ofa can bottle, a height of the first thread which is disposed near thetip of the mouth section of the bottle can member should be formed lowerthan the height of other threads in a predetermined angle range when thethread section is formed.

According to a method for forming the mouth section of the bottle canmember according to the present invention, when the thread section isformed, if the height of the first thread which is disposed near the tipof the mouth section of the bottle can member is formed to be lower thanthe other stage of threads in a predetermined angle range, when thebottle can member is compressed in a step for putting the cap under thiscondition, the first thread is compressed to be crushed; thus, thediameter id enlarged. Therefore, the height of the first thread isapproximately equal to the height of the other thread; thus, it ispossible to form all the threads desirably.

The invention according to a seventh aspect of the present invention ischaracterized to be a method for forming the mouth section of the bottlecan member according to a second aspect of the present invention inwhich a predetermined angle range is within 90 degrees from the threadstart point of the thread section.

According to a method for forming the mouth section of the bottle canmember according to the present invention, the height of the firstthread is lower than the height of the other thread with in a range of90 degrees from the thread start point of the thread section; therefore,it is possible to cover the first thread reliably in a range where thethread is crushed such that the diameter should be enlarged by acompressing force in a step for putting the cap.

The invention according to an eighth aspect of the present invention isa thread forming device which comprises a core which contacts an innersurface of a mouth section of the bottle can member and has a threadforming section for disposing a thread section which is supposed to beformed in the mouth section on an outer periphery, and an outer memberwhich contacts the outer periphery of the mouth section and has a threadforming section which has a corresponding shape to the thread formingsection of the core around the outer periphery such that the core andthe outer member rotate around an axial center of the bottle can memberwhile sandwiching the mouth section, a thread forming section whichforms a first thread in the thread area in the mouth section is formedlower than the other thread forming section in a predetermined anglerange.

According to the thread forming device according to the presentinvention, the first thread forming section of the core is formed so asto be lower than the other stage of the thread forming section in apredetermined angle range; therefore, it is possible to form the firstthread to be lower than the other stage of thread on an outer peripheryof the mouth section of the bottle can member reliably.

An invention according to a ninth aspect of the present invention ischaracterized in that, in a bottle can member in which a mouth sectionis disposed in an aperture section and a thread section is formed havinga thread number which has a thread area which has a plurality of stageson an outer periphery of the mouth section, the height of the firstthread in the thread area in the tread section is formed so as to belower than the height of the thread in the other stage in apredetermined angle range.

According to the bottle can member according to the present invention,the height of the first thread which is disposed on the mouth section isformed so as to be lower than the height of the thread in the otherstage in a predetermined angle range; therefore, if a diameter of themouth section is enlarged in a step for putting the cap, it is possibleto dispose the height so as to be equal approximately to the height ofthe thread in the other stage.

An invention according to a tenth aspect of the present invention is abottle can member which is characterized in that, in a area which isexcept an area which overlaps the plurality of stages and an incompletethread section in the thread end section, a mouth section is disposed inthe aperture section, and a thread section which has a thread numbersuch that the thread area is formed so as to have a plurality of stagesof thread areas from the tip of the mouth section toward a direction ofa bottom of the can, and the height of the first thread in the threadsection is formed so as to be lower than the height of the secondthread.

According to the bottle can member according to the present invention,the height of the first thread is formed so as to be lower than theheight of the second thread; therefore, if the diameter of the mouthsection is crushed by a compressing force in a step for putting the cap,the heights of the threads can be formed so as to be approximately equalrespectively.

An invention according to an eleventh aspect of the present invention ischaracterized in comprising a bottle can member and a cap which is puton a mouth section of the bottle can member.

According to the bottle according to the present invention, the heightof the thread in the thread section which is disposed on the mouthsection is approximately equal to the height therearound; therefore, ifthe cap is put there, the cap is not depositioned due to a positivepressure in the bottle can member, nor the bridge is not broken. Inaddition, it is possible to obtain a desirable bottle by which it ispossible to put and detach the cap smoothly.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a general view for a bottle can member according to a firstembodiment of the present invention.

FIG. 2A provides an exploded view of the bottle can member of FIG. 1 anda cap which may be fastened to a mouth section of the bottle can member.

FIG. 2B provides a view of the bottle can member and cap of FIG. 2A, inwhich the cap is fastened to the mouth section of the bottle can member.

FIG. 3 is a cross section for explaining the cap which is put on thebottle can member.

FIG. 4 is an enlarged view for explaining a bottle in which the cap isput on the bottle can member.

FIG. 5 is an enlarged cross section for a mouth section of the bottlecan member.

FIGS. 6A to 6C are views for explaining a conventional bottle can memberand the cap.

FIGS. 7A to 7D are views for conventional thread sections which areformed on the mouth section of the bottle can member.

FIG. 8 is a view for explaining an effective conventional threadsection.

FIG. 9 is a cross section for showing an important part of the mouthsection of a metal bottle can member according to the first embodimentof the present invention.

FIG. 10 is a view for explaining a thread winding section by viewing amale thread section upwardly.

FIG. 11 is a cross section for a part of a conventional metal bottle canto which a cap is put.

FIG. 12 is a view for explaining a thread forming device for performingthe present invention.

FIG. 13 is a view for showing a condition under which the thread sectionis formed in the mouth section of the bottle can member by the threadforming device.

FIG. 14 is an external view for showing a core for the thread formingdevice.

FIG. 15 is an enlarged view for a thread forming section in the coreshown in FIG. 14.

FIG. 16 is a corresponding view for showing an arrow A which is shown inFIG. 14.

FIG. 17 is a view for showing a condition under which the thread sectionis formed in the mouth section of the bottle can member by the threadforming device.

FIG. 18 is an enlarged view for explaining an important part which showsa thread section which is disposed in the mouth section of the bottlecan member.

FIGS. 19A to 19C are views for showing conventional steps until forminga thread section on the bottle can member.

FIG. 20 is a view for explaining a cap which is put on the bottle canmember which has a thread section.

FIG. 21 is a view for explaining a conventional condition undercondition that a thread section which has a thread number 2.2 on themouth section of the bottle can member.

FIG. 22 is a view for explaining a problem which has occurred in thethread section of the bottle can.

DETAILED DESCRIPTION OF THE INVENTION

Preferable embodiments for A metal bottle can, a thread forming device,and a method for forming a mouth section are explained below withreference to drawings. However, the present invention is not limited tothe embodiments below; thus, for example, it may be acceptable ifstructural elements in these embodiments may be combined appropriately.

Hereinafter, the embodiments of the present invention are explained withreference to the drawings. FIGS. 1 to 5 are views for showing a bottlecan member according to the first embodiment and a bottle in which a capis put on the bottle can member. FIG. 1 is a view for showing an entirebottle can member. FIG. 2 is a view for explaining FIGS. 2A and 2Billustrate a relationship between the bottle can member and the cap.FIG. 3 is a cross section for explaining steps for putting the cap onthe bottle can member. FIG. 4 is an enlarged view for showing the bottlein which the cap is put on the bottle can member. FIG. 5 is an enlargedcross section for the mouth section of the bottle can member.

The bottle can member 1 according to the present embodiment serves forfilling a carbonated beverage and a fruit beverage thereinside which ismade of an aluminum member or an aluminum alloy such that the mouthsection 12 is formed on an upper section of the bottle can member 11 asshown in FIG. 1.

A thread section 13 is disposed on an upper outer periphery of the mouthsection. An expanding section 14 is formed so as to be lower than thethread section 13. Simultaneously, a neck section 15 is formedtherebeneath. The thread section 13 is formed such that a diameter ofthe mouth section 12 which is disposed on the bottle can member 11 isenlarged so as to form the enlarged-diameter section, and after that, adiameter of a section in which the thread is supposed to be formed isdecreased, a thread is formed by a thread forming device (which is notshown in the drawings) on such a diameter-decreased section, thediameter of the expanding section 14 is not decreases. Furthermore, whenthe thread is formed on the thread section 13, the thread section 13 isformed by the diameter-enlarged section in which a thread is not formed(See FIG. 6D).

In addition, when a cap member 21 which is formed in a bottomedcylindrical shape as shown in FIG. 2A covers the mouth section 12, thecap 20 is put on the mouth section 12 as shown in FIGS. 2B and 4 bywinding up the cap member 21 by a capping device 30 as shown in FIG. 3.By doing this, the cap 20 seals an end of the aperture in the mouthsection 12.

An upper section of the cap member 21 is closed by a ceiling plate 22 asshown in FIG. 2A before it is put thereon. Simultaneously, a lowersection has a cylindrical shape which has an aperture orthogonally so asto be disposed downwardly. A liner 23 (See FIGS. 3 and 4) is attached inan inner surface of the ceiling plate 22. A cap main body lower section25 is disposed on a lower end of the cap member 21 via a bridge section24. A plurality of scores 24 a and a bridge 24 b are disposed in thebridge section 24 alternately in a circumferential direction of the capmember 21

In the present embodiment, an effective thread number in the threadsection 13 which is disposed on the mouth section 12 of the bottle 11 isformed to be 2.2. That is, the thread section 13 is formed such that,when a diameter-enlarged section is formed in the mouth section 12, athreading roller of the thread forming device moves rotatively along acircumference of an enlarged-and-decreased-diameter section. Such anenlarged-and-decreased-diameter section is compressed so as to form athread peak and a thread valley separately. In such a case, as shown inFIGS. 2 and 4, the effective thread number between a start position 13 aand an end position 13 b which serve effectively for the thread section13 is formed to be 2.2 in the mouth section 12. Here, in the presentinvention, it is acceptable if the effective thread number is 2.0 to2.5.

The effective thread section in the thread section 13 is definedsimilarly to the effective thread section which is shown in aconventional example as shown in FIGS. 6 a to 6 c such that the threadsection covers from the start position 13 a (an effective thread startpoint x1 in FIG. 8) to the end position 13 b (an effective thread endpoint x2 in FIG. 8). Also, an outer diameter of the thread section ofthe mouth section 12 is defined similarly to the outer diameter b whichis shown in FIG. 6 a which shows a conventional example. In the bottlecan member 11 which has such a thread section 13, an outermost diameterof the thread section 13 which is formed on the mouth section 12 is 28to 38 mm. Also, the thickness of the mouth section 12 is 0.25 to 0.4 mm.The thread section 13 which has the effective thread number 2.2 isformed by eight-thread per inch pitch.

Therefore, if the cap member 21 is put on the mouth section 12 as shownin FIG. 2B and the cap 20 is put around an outer periphery of the capmember 21 by forming the cap thread section 26 by using a capping device30 as shown in FIG. 3, a thread section which has the effective threadnumber 2.2 is formed on the cap 20.

Also, as shown in FIG. 5, a curl section 27 of which tip is bentoutwardly is formed on a tip of the mouth section and a slant section 28of which diameter is enlarged toward downwardly from the curl section 27are formed. The thread start point W1 (See FIG. 8) serves a point whichis an approximate outermost diameter for the thread section 13. An outerdiameter which passes through the thread start point W1 is indicated byD1. An outer diameter which passes through an outermost diameter sectionof the curl section 27 is indicated by a curl section outer diameter D2.Also, h indicates a thread start point height between an upper endsurface 29 of the bottle can member 11 and the thread start point W1. Tindicates a curl section height between the upper end surface 29 and thelowest end point T1 which is disposed outside of the curl section 27.

With reference to FIG. 5, it can be seen that the outermost diametersection of the curl section 27 at the diameter D2 extends vertically ina linear direction that is substantially parallel to a central axis O.As a result, it is evident that linear vertical portion of the outermostdiameter section of the curl section 27 defines a tangent plane that issubstantially parallel to the central axis O.

The slant angle θ of the slant section 28 is an angle which is formed byan inclination which is disposed toward an upper section of the mouthsection from the thread start point W1 and the central axis O. Anaverage angle for the slant section 28 between the lowest end point T1which is disposed outside of the curl section 27 and the thread startpoint W1 is used for such a slant angle θ.

The slant angle θ is measured by using a contracer CDH-400 (a product ofMitutoyo Corporation, trademark registered) such that a predeterminedsection from the thread start point W1 to the lowest end section T1 ismeasured. That is, a contour shape of the slant section 28 is measuredin a direction O for the central axis by the contracer such that a lineis determined by using a least square method according to the measuredcontour shape under condition that a slant angle θ is formed by the lineand the central axis O.

Also, there is a relationship which is indicated by a formula F1 betweenthe above explained slant angle θ and the thread start point height h.

$\begin{matrix}{h \approx {{{\tan\left( {90 - \theta} \right)}\frac{\left( {{D1} - {D2}} \right)}{2}} + T}} & {{Formula}\mspace{14mu}{F1}}\end{matrix}$

It is understood that, according to the Formula F1, when an outerdiameter D1 of the thread, an outer diameter D2 of the curl section, andthe height T of the curl section are fixed, the thread start pointheight h is determined if the slant angle θ is determined, and thethread start point height h is decreased if the slant angle θ isincreased. By doing this, the lower limit of the slant angle θ is anupper limit for the thread start point height h. The lower limit for thethread start point height h is an upper limit for the slant angle θ. Itis acceptable if a range for his 0.7≦(D1−D2)/h=≦1.3. More preferably,the range for the h should be 3.24≦h≦5.6 mm.

As mainly shown in FIG. 3, the capping device 30 is provided with apressure block 35 which compresses the ceiling plate 22 of the capmember 21 which covers the bottle can member 11 downwardly, an RO roller32 which compresses the cap member 21 to the mouth section 12 from aperiphery therearound and forms the cap thread section 26 by winding theouter periphery of the cap member 21 along the thread section 13 of themouth section 12, and a PP roller 33 which forms a pilfer proof sectionby winding the cap men body lower section 25 of the cap member 21 arounda lower part of the expanding section 14 from an outer periphery.

Here, the compressing member 35 is provided with a compressing member 31which compresses the ceiling plate 22 of the cap member 21 so as to beconnected to a pressure shaft 37 via a compressing spring member 34 suchthat when the cap 20 is put, a compressing force for compressing theceiling plate 22 of the cap member 21 which covers the mouth section 12can be varied according to a size of the diameter of the mouth section12. The RO roller 32 and the PP roller 33 are rotative around the bottlecan member 11 and the cap member 21 by a supporting arm 36.

In the bottle can member 11 according to the present embodiment, asexplained above, the effective thread number of the thread section 13which is disposed in the mouth section 12 is formed to be 2.2. The cap20 is put there; therefore, a shown in FIGS. 2A and 2B, the cap member21 which has a bottomed cylindrical shape is disposed so as to coverthereon. After that, the capping device 30 is driven. While the pressureblock 35 of the capping device 30 compresses the cap member 21 as shownin FIG. 3 in a direction toward the bottom section of the bottle canmember 11 and the RO roller 32 is rotated along a periphery of the mouthsection 12 so as to trace the thread section 13 of the bottle can member11. By doing this, as shown in FIG. 4, a cap thread section 26 is formedwhich corresponds to the thread section 13 of the mouth section 12 on anouter periphery of the cap member 21. Also, the cap main body lowersection 25 of the cap member 21 is wound around the expanding section bythe PP roller 33. By doing this, the cap 20 is put on the bottle canmember 11.

A load test and a leak test are performed by using the above explainedbottle can member 11 and the cap 20. The experiment is performed forthree variations for the bottle can members 11 and the caps 20 whichhave 38 mm size, 33 mm size, and 28 mm size while varying the slantangle θ and the thread start point height h. For the experiment, thebottle can member 11 is used which has 0.24 to 0.4 mm thickness, aneffective thread number 2.2 for an eight-pitch-per-inch which isdisposed for the thread section. A cap 20 to which a liner 23 isattached which is made of a polyethylene member or a polypropylenemember is used which has a tension strength such as 180 to 230 N/mm²,0.25 mm thickness.

In the load test, a force is applied gradually in an axial direction ofthe bottle can member 11. If the bottle can member 11 is folded by aforce which is under 1600 N, it is evaluated as a defect (X). If thebottle can member 11 is folded by a force which is over 1600 N, it isevaluated as an inspected product (◯). In the leak test, the weight ofthe bottle 10 is measured which is filled by 0.1 Mpa of inner pressureunder an ordinary temperature condition such that the weight is measuredunder an ordinary temperature condition after maintaining the bottle 10for an entire daytime under 37° C. condition. If the difference of theweight is under 0.2 mg, the bottle 10 is evaluated as an inspectedproduct (◯). If the difference of the weight is over 0.2 mg, the bottle10 is evaluated as a default product (x). Results of the experiments areshown in TABLE 1.

TABLE 1 Evaluation Evaluation Total h θ for Folding for leakingEvaluation φ 38 can 3.2 62.0 x ∘ x D1 = 38 mm 3.6 55.0 ∘ ∘ ∘ D2 = 33.4mm 4.6 40.0 ∘ ∘ ∘  T = 2 mm 5.6 33.0 ∘ ∘ ∘ 6.0 29.0 ∘ x x φ 33 can 3.1856.1 x ∘ x D1 = 33 mm 3.24 54.6 ∘ ∘ ∘ D2 = 29.5 mm 3.61 47.4 ∘ ∘ ∘  T =2 mm 4.68 33.2 ∘ ∘ ∘ 4.74 32.5 ∘ x x 5.54 26.3 ∘ x x φ 28 can 3.2 59.0 x∘ x D1 = 28 mm 3.4 55.0 ∘ ∘ ∘ D2 = 24.0 mm 3.6 51.0 ∘ ∘ ∘  T = 2 mm 4.637.0 ∘ ∘ ∘ 5.1 33.0 ∘ ∘ ∘ 5.6 29.0 ∘ x x

It is understood that, in the TABLE 1, if the thread start point heighth becomes short; that is, if the slant angle θ becomes larger, thereoccurs a folding, and if the thread start point height h becomes long;that is, if the slant angle θ becomes smaller, there occurs a leaking.By doing this, the range for the thread start point height h and theslant angle θ in which there do not occur a folding or a leaking isevaluated as ◯, and the rest of them are evaluated as x. For rangeswhich is evaluated as ◯ in the total evaluation are such that 3.6mm≦h≦5.6 mm and 33.0°≦θ≦55.0° in a bottle 10 which has 38 mm of an outerdiameter D1 of the thread, 3.24 mm≦h≦4.74 mm and 32.5°≦θ≦54.6° in abottle 10 which has 33 mm of an outer diameter D1 of the thread, and 3.4mm≦h≦5.1 mm and 33.0°≦θ≦55.0° in a bottle 10 which has 33 mm of an outerdiameter D1 of the thread.

As explained above, the bottle 11 according to the present embodiment isformed so as to have the effective thread number of the thread section13 which is disposed on the mouth section 12 to be 2.2. Therefore, therethe bending section of the thread section 13 is not disposed partiallydue to a pressure of the pressure block in a step for putting the cap20. By doing this, the height positions for compressing the RO roller tothe cap 20 are not unequal; thus, there does not occur a defect thread.Also, there are less sections in which there are three threads; thus,the bridge is hardly broken when the cap 20 is put thereon.

On the other hand, if the cap 20 is put on the bottle can member 11 anda pressure inside the bottle 10 is positive, a force which pushes thecap 20 from thereinside of the mouth section 12 of the bottle can member11. As explained above, the effective thread number for the threadsection 13 of the mouth section 12 and the cap thread section 26 are 2.2such that the thread section 13 and the cap thread section 26 areengaged by a constant force. Thus, the cap 20 is not disposed to thebottle can member 11 partially; thus, there is not a concern in that thebridge section 24 of the cap 20 may be broken. Also, the torque foropening the cap does not increase unnecessarily.

As a result, according to the present embodiment, it is possible to putthe cap 20 on the bottle can member 11 desirably; thus, it is possibleto maintain a desirable condition for the cap 20 after it is putthereon. Therefore, it is possible to solve a conventional problem whichis caused by the thread number of the thread section 13 of the bottlecan member 11; therefore, it is possible to enhance a reliability of thebottle 10.

Also, the bottle can member is formed so as to be in a range of thethread start point height h such as 3.24≦h≦5.6 mm; therefore, it ispossible to obtain a desirable contact between the curl section 27 andthe liner 23 under a predetermined inner pressure. That is, the intervalbetween the cap thread section 26 of the cap 20 and the ceiling plate 22extends due to the inner pressure. Such an extension amount isdetermined by the thread start point height h; thus, it is possible toset the extension amount in which there is not a leaking by setting thethread start point height h within the above range. By doing this, it ispossible to form the bottle can member 11 which has a desirable sealingcondition under a predetermined inner pressure condition.

Also, the slant angle θ is formed so as to be in a range of 33°≦θ≦55°,thus, it is possible to a load resistance which can endure the force forcompressing the cap 20 in a step for putting the cap 20. Also, the mouthsection 12 is formed so as to have the effective thread number to be 2.0to 2.5, thus, the cap 20 is not disposed to be shifted undesirably;therefore, it is possible to form the bottle can member 11 to which thecap 20 is put reliably and restrict the increase in the torque foropening the cap.

Here, in the embodiments shown in the drawings, an example is shown inwhich the effective thread number is 2.2 which is formed in the threadsection 13 which is formed in the mouth section 12 of the bottle canmember 11 and the cap 20. It is acceptable if the effective threadnumber is at least 2.0 or higher to be lower than 2.5. Furthermore, aslong as the effective thread number is 2.0 to 2.3, the incomplete threadsection does not overlap in an axial direction; thus, it is possible toform the thread. Therefore, there are less sections in which there arethree threads; thus, it is preferable.

Therefore, in the present invention, if the outermost diameter of thethread section 13 which is formed on the mouth section 12 of the bottlecan member 11 is 28 to 38 mm, the thickness thereof is 0.25 to 0.4 mm,and the effective thread number is 2.0 to 2.5, more preferably 2.2 to2.3, it is possible to realize the above operational effects.

Hereinafter, the embodiments of the present invention are explained withreference to the drawings.

A partial cross section for a mouth section of a metal bottle can isshown in FIG. 9. In the mouth section of the metal bottle can(hereinafter called a bottle can for short) 102, the tip is foldedoutwardly so as to dispose the curl section 107 such that a surfacewhich is disposed in an uppermost on a curved surface which forms thecurl section 107 is an upper end surface 120. A slant section 121 isdisposed of which diameter increases toward downwardly from the curlsection 107; thus, a male thread section 105 is disposed which has athread peak 122 and a thread valley 123 beneath the slant section 121.

Also, a part of the slant section 121 protrudes gradually toward acircumferential direction on an upper end section of the male threadsection 105. The protrusion height increases until reaching thepredetermined height of the thread 122. Thus, the thread start endsection is formed such that the depth of the thread valley 123 decreasesgradually toward the circumferential direction in a lower end section ofthe male thread section 105; thus, the thread end section is formed.

In a cross section which is shown in FIG. 9, the thread start point W101serves a point which is an approximate outermost diameter of the thread122 under condition that the outer diameter D101 of the thread indicatesan outer diameter which passes through the thread start point W101 andan outer diameter D102 of the curl section indicates an outer diameterwhich passes through the outermost section of the curl section 107.Also, h indicates a thread start point height between an upper endsurface 120 of the bottle can member 102 and the thread start pointW101. T indicates a curl section height between the upper end surface120 and the lowest end point T101 which is disposed outside of the curlsection 107.

The slant angle θ of the slant section 121 is an angle which is formedby an inclination which is disposed toward an upper section of the mouthsection from the thread start point W101 and the central axis O. Anaverage angle for the slant section between the lowest end point T101which is disposed outside of the curl section 107 and the thread startpoint W101 is used for such a slant angle θ.

The slant angle θ is measured by using a contracer CDH-400 (a product ofMitutoyo Corporation, trademark registered) such that a predeterminedsection from the thread start point W101 to T101 is measured.

Also, there is a relationship which is indicated by a formula F1 betweenthe above explained slant angle θ and the thread start point height h.

Here, the outer diameter D101 of the thread in the present embodimentcorresponds to the outer diameter D1 of the thread in the firstembodiment. The outer diameter D102 of the curl section corresponds tothe outer diameter D2 of the curl section of the first embodiment. Thethread start point W101 corresponds to the thread start point W1 of thefirst embodiment. The lowest end point T101 corresponds to the lowestend point T1 of the first embodiment.

Also, the thread start end section Y, the thread end section Z, and theeffective thread winding section X are explained by using the drawing inwhich the male thread section 105 is viewed upwardly which is shown inFIG. 10. The depths for the thread peak 122 and the thread valley 123for the thread start end section Y and the thread end section Z are notconstant in a circumference direction; thus, it is an incomplete threadsection. In contrast, the perfect thread section W is formed so as tohave a predetermined thread height and the thread depth. The incompletethread in the thread start end section Y is formed so as to protrudefrom the end point Y101 of the thread start end section Y so as to behigher gradually at the thread start point W101 of the perfect threadsection W at the predetermined height of the thread 122. Also, theincomplete thread valley in the thread end section Z is formed so as tohave a depth which should be shallower from the thread end point W102 ofthe perfect thread section W and the depth disappears at the end pointZ102 of the thread end section Z; thus, it is a plain surface.

The effective thread section X includes all the sections from theeffective thread start point X101 in the middle of the thread start endsection Y, the perfect thread section W so as to be a thread sectionwhich covers the effective thread end point X which is in the middle ofthe thread end section Z. The effective thread start point X101 is across section which is formed by a bisector L101 which is formed in anacute angle/a of the thread start end section Y which is formed by theend point Y101, the center point C, and the thread start point W101 andthe thread start end section Y. Also, effective thread start point X102is a cross section which is formed by a bisector L102 which is formed inan acute angle ∠β of the thread end section Z which is formed by thethread end point W102, the center point C, and the end point Z102 andthe thread end section Z.

A load test and a leak test are performed by using the above explainedbottle can 102 and the cap 103. The experiment is performed for threevariations for the bottle can members 102 and the caps 103 which have 38mm size, 33 mm size, and 28 mm size of diameter D101 while varying theslant angle θ and the thread start point height h. For the experiment,the bottle can member 2 is used which has 0.24 to 0.4 mm thickness, aneffective thread number 2.2 for an eight-pitch-per-inch which isdisposed for the male thread section 5. A cap 103 is used which has atension strength such as 180 to 230 N/mm².

In the load test, a force is applied gradually in an axial direction ofthe bottle can 102. If the bottle can 102 is folded by a force which isunder 1600 N, it is evaluated as a defect (x). If the bottle can 102 isfolded by a force which is over 1600 N, it is evaluated as an inspectedproduct (◯). In the leak test, the weight of the capped bottle 101 ismeasured which is filled by 0.1 Mpa of inner pressure under an ordinarytemperature condition such that the weight is measured under an ordinarytemperature condition after maintaining the capped bottle 101 for anentire daytime under 37° C. condition. If the difference of the weightis under 0.2 mg, the capped bottle 101 is evaluated as an inspectedproduct (◯). If the difference of the weight is over 0.2 mg, the cappedbottle 101 is evaluated as a default product (x). The detail of theresult of the experiment is shown in the above TABLE 1.

It is understood that, in the TABLE 1, if the thread start point heighth becomes short; that is, if the slant angle θ becomes larger, thereoccurs a folding, and if the thread start point height h becomes long;that is, if the slant angle é becomes smaller, there occurs a leaking.By doing this, the range for the thread start point height h and theslant angle θ in which there do not occur a folding or a leaking isevaluated as ◯, and the rest of them are evaluated as X. For rangeswhich is evaluated as ◯ in the total evaluation are such that 3.6mm≦h≦5.6 mm and 33.0°≦θ≦55.0° in a capped bottle can 1 which has 38 mmof an outer diameter D1 of the thread, 3.24 mm≦h≦4.74 mm and32.5°θ≦54.6° in a capped bottle 1 which has 33 mm of an outer diameterD1 of the thread, and 3.4 mm≦h≦5.1 mm and 33.0°≦θ≦55.0° in a cappedbottle can 1 which has 33 mm of an outer diameter D1 of the thread.

Also, the capped bottle can 1 of the present embodiment is formed so asto be in a range of the thread start point height h such as 3.24≦h≦5.6mm; therefore, it is possible to obtain a desirable contact between thecurl section 107 and the liner 112 under a predetermined inner pressure.That is, the interval between the female thread section 104 of the cap103 and the ceiling plate 108 extends due to the inner pressure. Such anextension amount is determined by the thread start point height h; thus,it is possible to set the extension amount in which there is not aleaking by setting the thread start point height h within the aboverange. By doing this, it is possible to form the bottle can 102 whichhas a desirable sealing condition under a predetermined inner pressurecondition. Also, it is possible to obtain a desirable contact conditionby setting the thread start point height h in the above range in a casein which a knurl section 113 is formed between the female thread section109 of the cap 103 and the ceiling surface section 108.

Also, the slant angle θ is formed so as to be in a range of 33°≦θ≦55°,thus, it is possible to a load resistance which can endure the force forcompressing the cap 103 in a step for putting the cap 103. Also, themouth section 104 is formed so as to have the effective thread number tobe 2.0 to 2.5, thus, the cap 103 is not disposed to be shiftedundesirably; therefore, it is possible to form the capped bottle can 102to which the cap 103 is put reliably and restrict the increase in thetorque for opening the cap.

Here, in the present embodiment, explanations are made by using thecapped bottle can 201 which has three outer diameters D101 38 mm, 33 mm,and 28 mm for the thread. It is acceptable if the present invention isused for the capped bottle can 101 which has different outer diameterD101 for the thread.

Hereinafter, a third embodiments of the present invention are explainedwith reference to the drawings. FIGS. 12 to 17 are views for showing amethod for forming a mouth section according to a third embodiment ofthe present invention. FIG. 12 is a view for explaining a thread formingdevice for performing a method for forming a mouth section. FIG. 13 is aview for explaining a condition for forming a thread section in themouth section of the bottle can member by the thread forming device.FIG. 14 is an external view for showing a core of the thread formingdevice. FIG. 15 is an enlarged view for the thread forming section inthe core which is shown in FIG. 14. FIG. 16 is a view which correspondsto an arrow A which is shown in FIG. 14. FIG. 17 is a view for showing acondition under which the thread section is formed in the mouth sectionof the bottle can member.

Before explaining a method for forming a mouth section according to thepresent embodiment, the bottle can member 1 which is handled in a methodfor forming the mouth section serves for filling a content such as acarbonated beverage and a fruit beverage thereinside. The bottle canmember 1 is formed so as to be in a bottomed cylindrical shape by a thinmetal member which is made of an aluminum member or an aluminum alloy.After that, a mouth section 202 of which diameter is smaller than adiameter of a can body is formed in an aperture section of the bottlecan member 201. After that, a thread section 203 is formed around aperiphery of the mouth section 202 by a thread forming device 210 (SeeFIGS. 19A to 19C).

In the present invention, the effective thread number is 2.0 to 2.5 forthe mouth section 202 of the bottle can member 201.

In addition, as a general structure, the thread forming device forperforming a method for forming the mouth section is provided with acore 211 which contacts an inner periphery surface of the mouth section202 of the bottle can 201, and an outer core 212 (outerside member)which contacts an outer periphery surface. The thread section 203 isformed around the mouth section 202 by rotating the core 211 and theouter core 212 around an axial center O of the bottle can member 201while sandwiching the mouth section 202 by the core 211 and the outercore 212.

Thread forming sections 221, 222 which have concave and convex sectionsfor forming a thread section 203 on its outer periphery surface areformed in a spiral manner and in a corresponding shape respectively asshown in FIGS. 12 and 13 in the core 211 and the outer core 212 so as tobe rotated by a driving structure which is not shown in the drawings.

Although it is not described in the drawings, a work supporting section230 has a chucking function so as to support a bottle can member 201 asa workpiece.

In the thread forming device 210, when the bottle can member 201 inwhich a bottom section is supported by a die ring 231 of the worksupporting section 230 is positioned in a corresponding position asshown in FIG. 12, at first, a cylindrical surface which is not shown inthe drawing is engaged to a can body section from a shoulder section ofthe bottle can member 201 by progressing the work supporting section230. Furthermore, the core 211 moves to an inner periphery surface ofthe mouth section 202 of the bottle can member 201 so as to contactthere, and the outer core 212 moves to an outer periphery surface of themouth section 202 so as to contact there. By doing this, the core 211and the outer core 212 sandwich the mouth section 212. Under the abovecondition, furthermore, the entire device 210 rotates around an axialcenter O. By doing this, the thread section 203 is formed in the mouthsection 202.

In such a case, the thread number for the thread section 203 which isformed in the mouth section 202 of the bottle can member 201 is formedto be 2.2. In the thread section 203 which has 2.2 thread number asshown in FIG. 14, there is a thread area L which comprises a firstthread 203 a, a second thread 203 b, and a third thread 203 c on anouter periphery surface of the mouth section 202. Therefore, the threadforming section 221 which has a concave and convex section which isdisposed on the core 211 is formed so as to correspond to the threadsection 203 as shown in FIG. 14.

In the present embodiment, when the thread section 203 is formed so asto face an outer periphery of the mouth section 202, the first thread203 a is formed as shown in FIG. 17 so as to be lower than the secondthread 203 b and the third thread 203 c by a slight difference such as adimension A.

That is, as shown in FIG. 15, in the thread forming section 221 of thecore 211, a height of the thread forming section 221 a in a first stageis formed so as to be lower than the height of the thread formingsection 221 b in the second stage and the height of the thread formingsection 221 c in the third stage by a slight difference such as adimension A. By doing this, when the thread section 203 is formed in themouth section 202 of the bottle can member 201 by the core 211 and theouter core 212, as shown in a line in FIG. 17, the thread 203 a in thefirst stage which is disposed near the thread start section 203A of themouth section 202 is formed lower than the thread 203 b in the secondstage and the thread 203 c in the third stage by a slight differencesuch as a dimension Δ in advance.

In such a case, a height such as 0.8 mm for the thread is set, thedimension Δ is lower than such a thread height by approximately 0.1 mm.Therefore, it is approximately 0.7 mm. However, it should be selectedpreferably from a stricter point of view.

Also, in the thread forming section 221 of the core 211, a range inwhich the thread forming section 221 in the first stage is lower thanthe thread 221 b in the second stage and the third thread 221 c in thethird stage is indicated by an angle range a such as 90 degrees whichincludes the thread area L as shown in FIG. 16 in the presentembodiment. In such a case, under condition that the thread startsection 221A of the thread forming section 221 a in the first stage isindicated by 0 (zero) degree, the angle range α is 90 degrees from 0degree.

Here, in consideration of an area in which there is a possibility inthat a thread number of the thread section 203 varies and the thread iscrushed with regardless to the 90 degrees of the range, 360 degrees ofthe angle range is preferable. More preferably, the angle range 200 to300 degrees (α1) is preferable.

Here, the thread start section 221A of the thread forming section 221serves a section in which the thread section 203 which is formed in themouth section 202 works as a screw effectively which corresponds to thethread start section 203A of the thread section 203. Therefore, thethread end section 221B and the thread end section 203B of the threadsection 203 are formed correspondingly respectively.

Here, in FIGS. 1 to 6, the same reference numerals are add to the samesections as those in FIGS. 19A to 22.

This thread forming device 210 is formed in the above manner; therefore,an embodiment for a method of the present invention is explained nextwith reference to operations for the thread forming device 210.

First, in order to dispose a thread section 203 on the bottle can member201, the bottle can member 201 in which a bottom section is supported ata work supporting section 230 which is formed by a die ring and a ringhollow flexible member which are not shown in the drawings is positionedin a corresponding position. A cylindrical surface which is not shown inthe drawing is engaged to a shoulder section and a can body section ofthe bottle can member 201 by progressing the work supporting section230. Furthermore, the core 211 moves to an inner periphery section ofthe mouth section 202 of the bottle can member so as to contact there.Simultaneously, the core 212 moves to an outer periphery section of themouth section 202 so as to contact there. By doing this, the core 211and the outer core 212 sandwich the mouth section 202. Furthermore,under such a condition, the entire device rotates around the axialcenter O. By doing this, a thread section 203 which is shown by a linein FIG. 17 is formed in the mouth section 202.

In such a case, the thread section 203 which has 2.2 thread number isformed along an outer periphery surface of the mouth section 202 byrotating the core 211 and the outer core 212, the height of the threadforming section 221 a in the first stage of the core 211 is lower thanthe thread forming section 221 b in the second stage and the threadforming section 221 c in the third stage. Therefore, the thread 203 a islower than the height of the thread 203 b in the second stage and thethird thread 203 c in the third stage respectively among the threadareas which are disposed in the mouth section 202.

After the thread section 203 is formed on an outer periphery of themouth section 202 in such a manner, if a step for forming the cap isperformed by a cap putting device which is not shown in the drawing inorder to dispose a curl section 208 on a tip of the mouth section 202which has the thread section 203, the cap putting device folds the tipof the mouth section 202 from thereoutside to thereinside so as to formthe curl section 208 (FIGS. 20 and 22) while compressing the bottle canmember 1 by the cap putting device. Therefore, the tip of the mouthsection 202 receives a compressing force, and a thread 203 a in thefirst stage in the mouth section 202 is crushed. By doing this, adiameter of the thread 203 a in the first stage is enlarged in a mannerwhich is shown in a dotted line shown in FIG. 17 instead of a line.

In such a case, as explained above, the thread 203 a in the first stagein the mouth section 2 is formed lower than the thread 203 b in thesecond stage and the thread 203 c in the third stage by a dimension Δ inadvance. Therefore, if a diameter is enlarged by a compressing forcewhich is generated in a step for putting the cap, the height isapproximately equal to the height of the thread 203 b in the secondstage and the height of the thread 203 c in the third stage as a result.

Therefore, according to the present invention, if a compressing force isapplied in a step for putting the cap on a tip of the mouth section 202after the thread 203 a in the first stage in the thread section 203 ofthe thread section 202 is formed lower in advance, it is possible toform the height of the thread 203 a in the first stage, the height ofthe thread 203 b in the second stage, and the height of the thread 203 cin the third stage approximately equally by such a compressing force;therefore, it is possible to equalize the height of the threadsapproximately.

Therefore, if the cap 205 is put on such a bottle can member 201, thecap 205 is formed in a bottomed cylindrical shape in which a diameter ofthe ceiling plate and a diameter of an aperture end are approximatelythe same. Therefore, the user can close the cap smoothly after openingthe bottle can member 201; thus, the user may not feel anyuncomfortness. Therefore, it is possible to solve a conventional problemin that the cap may be deformed in an undesirable conical shape. Thus,it is possible to enhance the reliability.

In addition, according to the thread forming device 210, it is possibleto form the thread 203 a in the first stage in the thread section 203 ofthe mouth section 202 in advance by forming only the height of thethread forming section 221 a in the first stage in the core 211 so as tobe lower than other thread forming sections 221 b and 221 c. Thus, it ispossible to form the thread section 203 reliably in which it is possibleto close the cap desirably.

FIG. 18 is an enlarged view for explaining an important part which showsa thread section which is disposed in the mouth section of the bottlecan member according to a second embodiment of the present invention.

If the thread section 203 which has a thread number 2.2 is formed on themouth section 202 of the bottle 201, there are two stages of threadexcept the thread area in which there are three stages of thread.

The present embodiment takes the thread section 203 in which there aretwo stages of thread into consideration. Here, the height of the thread301 in the first stage is formed so as to be lower than the height ofthe thread 302 in the second stage.

That is, the thread 301 in the first stage is formed so as to be in anarea except an area (L) in which there are three stages and anincomplete thread section of the thread end section such that the heightof the thread 301 in the first stage should be lower than the thread 302in the second stage only by a dimension A. Therefore, the thread formingsection 221 of the core 211 in the thread forming device 210 is formedaccording to such a height and the height of the threads 301, 302.

According to the present embodiment, the height of the thread 301 in thefirst stage is formed so as to be lower than the height of the thread302 in the second stage. Therefore, it is possible to form the thread301 in the first stage and the thread 302 in the second stage so as tobe in an equal height approximately.

Also, in the embodiment which is shown in the drawing, an example isshown in which the thread section 203 is formed which has a threadnumber 2.2 in the mouth section 202 of the bottle can member 1 by thethread forming device 210. Such a structure can be used for variouscases in which the thread number is increased more than 2.2 such as thethread number 2.5. Thus, the present invention is not limited to theembodiments which are described here.

Here, in the embodiments which are shown in the drawings, an example isshown in which the thread forming device 210 uses the outer core 212which rotates around the axial center O together with the core 211 whilecontacting the outer periphery of the mouth section 202. It isacceptable if other outer member which can form the core 211 and thethread section 203 instead of the outer core 212. Thus, the presentinvention is not limited to the embodiments which are described here.

INDUSTRIAL APPLICABILITY

As explained above, according to the present invention, the effectivethread number for the thread section of the mouth section is formed tobe 2.0 to 2.5; therefore, the bridge is not broken if the cap is put onthe bottle can member. Thus, the cap is put desirably. Also, theeffective thread number is 2.0 to 2.5; therefore, a compression amountof the mouth section in an axial line direction is approximately equalover a circumference direction when the cap is put; thus, it is possibleto enhance the sealing condition.

1. A bottle can member which is made of metal in a cylindrical shape with a bottom section comprising: a thread section on a mouth section comprising: an outer diameter of the thread section which is formed on the mouth section is 28 to 38 mm; a thickness of the thread section is 0.25 to 0.4 mm; an effective thread number of the thread section is 2.0 to 2.5; a height “h” from a starting point of the thread in the thread section to an upper end surface of the mouth section is set to be in a range of 3.6≦h≦4.68 mm; and a curl section including an outermost diameter section, wherein an outer surface of the outermost diameter section defines a uniform and outermost diameter of the curl section with reference to a central axis of the bottle can member, and wherein a tangent plane to the outer surface of the outer most diameter section is substantially parallel to the central axis of the bottle can member.
 2. A bottle can member according to claim 1 wherein the thread section further comprises: a thread pitch of the thread section formed on the mouth section is 8 threads per an inch.
 3. A bottle can member according to claim 1 further comprising: a slant angle θ of a slant section is set to be in a range of 33°≦θ≦55°.
 4. A bottle wherein a cap is put on a mouth section of the bottle can member according to claim
 1. 5. A bottle can member which is made of metal in a cylindrical shape with a bottom section comprising: a thread section on a mouth section comprising: an outer diameter of the thread section which is formed on the mouth section is 28 to 38 mm; a thickness of the thread section is 0.25 to 0.4 mm; an effective thread number of the thread section is 2.0 to 2.5; a height “h” from a starting point of the thread in the thread section to an upper end surface of the mouth section is set to be in a range of 3.6≦h≦4.68 mm; and a curl section including an outermost diameter section, wherein an outer surface of the outermost diameter section defines a uniform and outermost diameter of the curl section with reference to a central axis of the bottle can member, and wherein a tangent plane along the outer surface of the outermost diameter section is substantially parallel to the central axis of the bottle can member, and wherein a height of a first thread in the thread section set to be lower than a height of a second thread in the thread section.
 6. A bottle can member according to claim 5 wherein: the height of the first thread in the first thread section is not set to be lower than a height of the second thread in an area which overlaps a plurality of stages and an incomplete thread section in a thread end section.
 7. A bottle comprising the bottle can member according to claim 6 and a cap which is put on the mouth section of the bottle can member.
 8. A bottle comprising the bottle can member according to claim 5 and a cap which is put on the mouth section of the bottle can member.
 9. A DI can member which is made of metal in a cylindrical shape with a bottom section comprising: a thread section on a mouth section comprising: an outer diameter of the thread section which is formed on the mouth section is 28 to 38 mm; a thickness of the thread section is 0.25 to 0.4 mm; an effective thread number of the thread section is 2.0 to 2.5; and a height of a first thread in the thread section is set to be lower than a height of another thread.
 10. A DI can member according to claim 9 further comprising a height of a first thread in the thread section set to be lower than a height of another thread by approximately 0.1 mm. 